三维有序结构的金掺杂纳米TiO_2修饰电极用于H_2O_2的测定

在ITO玻璃表面构建了三维有序多孔结构的金掺杂纳米Ti O2薄膜(3DOM GTD/ITO),同时制备了一种细胞色素c(Cyt c)酶生物传感器(Cyt c/3DOM GTD/ITO)。通过透射电镜(TEM)、扫描电镜(SEM)对修饰电极进行表征。紫外-可见光谱实验表明吸附在GTD上的Cyt c能够保持其生物活性,二级结构未被破坏。同时研究了Cyt c在3DOM GTD/ITO修饰电极表面的直接电化学及对H2O2的电催化行为。结果显示,Cyt c在3DOM GTD/ITO修饰电极上有显著的直接电化学响应,峰电流与扫描速度呈线性关系,说明该电极过程是表面电化学控制过程。Cyt c/3DOM GTD/ITO修饰电极对H2O2具有良好的催化性能,线性范围为3.0×10-7~1.70×10-5mol/L,检出限为3.6×10-8mol/L(S/N=3),响应时间为5 s,且该修饰电极具有较好的重现性和稳定性。     

磁性纳米微球-血红蛋白修饰电极的电化学行为及对H2O2电催化还原的研究

将天然高分子壳聚糖(CS)包裹碳包铁的磁性纳米微球(CFN/CS)修饰于玻碳电极表面,并利用戊二醛将血红蛋白(Hb)交联在CFN/CS上,制备了Hb-CFN/CS-GC电极。循环伏安法和电化学交流阻抗法实验结果表明,Hb在CFN/CS-GC电极表面仍保持较好的生物活性,能稳定有效地进行直接电子转移反应。电化学研究表明该修饰电极对H2O2有良好的电催化还原作用,在pH 7.0的磷酸盐(PBS)介质中,H2O2在5.2×10-5~2.3×10-3mol/L浓度范围内,其浓度与还原峰电流呈良好线性关系,检出限为8.7×10-6mol/L。该修饰电极有着良好的重现性和稳定性。     

Hb/Fe3O4/CILE修饰电极的制备及应用

以类离子液体碳糊电极(CILE)为基体电极,采用滴涂法和利用静电吸附作用,制备了Hb/Fe3O4/CILE修饰电极,研究了Hb的直接电化学及其电催化行为,建立了H2O2的计时安培测定新方法。结果表明:Hb在该修饰电极上,Hb呈现了一对准可逆的氧化还原峰,且其在该修饰电极表面表观覆盖度为2.65×10-9moL/cm2;电子转移速率常数为1.35/s;表观米氏常数为1.59×10-5mol/L。在1.0×10-6~4.0×10-5mol/L范围内,催化电流与H2O2浓度呈线性关系(r=0.9976),检出限为3.0×10-7mol/L(S/N=3)。     

HA-[CePy][PF6]-Mb/GCE修饰电极的制备与应用

将肌红蛋白(Mb)包埋在十六烷基吡啶六氟磷酸盐([CePy][PF6])与透明质酸(HA)混合得到的复合膜内,采用滴涂法将其修饰在玻碳电极(GCE)表面,制备了HA-[CePy][PF6]-Mb/GCE修饰电极,研究了Mb的直接电化学及电催化行为,建立了H2O2的计时安培测定新方法。结果表明,在0.1 mol/LPBS(pH 7.0)中,该修饰电极上产生了一对准可逆的氧化还原峰,电子转移速率常数(ks)为3.9/s,电极表面表观覆盖度(Γ*)为4.36×10-9mol/cm2,表观米氏常数(Km)为2.6×10-5mol/L;该修饰电极上的Mb对H2O2的还原表现出良好的电催化作用,催化电流与H2O2浓度在2.5×10-6～5.0×10-5mol/L范围内呈线性关系,检出限为8.0×10-7mol/L(S/N=3)。     

超氧化物歧化酶在纳米金/L-半胱氨酸修饰金电极上的电化学行为

通过L-半胱氨酸将纳米金修饰到金电极上,把超氧化物歧化酶(SOD)固定在修饰电极表面,制备了SOD-纳米金/L-半胱氨酸修饰电极。运用交流阻抗法、循环伏安法等方法表征了该电极,发现SOD在该电极上于0.15V和-0.05V左右产生较明显的氧化还原峰,在0.04～0.24V/s扫描速率范围内,其还原峰电流与扫描速速呈线性关系,表明该电极过程受吸附控制。研究了H2O2对SOD-纳米金/L-半胱氨酸修饰电极伏安行为的影响,发现该电极的还原峰电流与H2O2浓度在1.0×10-6～2.0×10-4mol/L范围内呈良好的线性关系,相关系数为-0.996,可用于对H2O2的分析检测。     

细胞色素c在Fe_2O_3修饰电极上的直接电化学和电催化特性

采用全氟磺酸树脂Nafion将金属氧化物Fe2O3颗粒细胞色素c(Cyt c)固定玻碳电极(GCE)表面,制备了Nafion-Cyt c-Fe2O3修饰的玻碳电极,构建了基于直接电子传递的过氧化氢生物传感器。在0.10mol/L pH7.0的磷酸盐缓冲溶液中,修饰电极的循环伏安曲线上显示出一对准可逆的氧化还原峰,式量电位为22mV。Cyt c在修饰电极表面的异相电子转移速率常数为1.21s-1。修饰后的电极对过氧化氢有良好响应,响应时间小于10s,电极的安培响应与过氧化氢浓度在2.0×10-6～3.0×10-3mol/L范围内成线性关系,检出限为1.0×10-6mol/L,米氏常数为1.35mmol/L,显示出较好的亲和力。     

新型1-烷基-2,3-二甲基咪唑六氟磷酸盐离子液体/过氧化氢酶电极电化学性能研究与应用

合成了5种新型1-烷基-2,3-二甲基咪唑六氟磷酸盐类离子液体,并以离子液体为介质制备空白电极及过氧化氢酶电极.采用循环伏安法研究电极电化学行为,结果表明离子液体有优良的电化学性质.离子液体空白电极的基体峰电流都在数nA范围内,电化学窗口大于4 V;不同离子液体酶电极的电化学行为存在明显差异.在5种离子液体中,仅有1-戊基-2,3-二甲基咪唑六氟磷酸盐能很好地保持酶活,呈现灵敏的电化学响应.此外,该酶电极还具有良好的稳定性,4 ℃保存30 天后,电化学性质没有明显变化.在0.1 mol/L的H3PO4缓冲溶液(pH 7.0)中,该酶电极还原峰电流随溶液中H2O2浓度的增加而增大.当H2O2浓度在3.17×10-6～12.4×10-6 mol/L之间,酶电极的还原峰电流符合线性关系,其检出限为1.1×10-6 mol/L.方法已用于环境水中痕量H2O2的测定.     

金掺杂聚L-半光氨酸修饰电极测定多巴胺

利用电化学聚合法将金和L-半胱氨酸修饰于玻碳电极表面,制成了金掺杂聚L-半胱氨酸修饰电极,研究了多巴胺(DA)在该修饰电极上的电化学行为。实验结果表明,在p H 5.0的磷酸盐缓冲溶液中,多巴胺在修饰电极上产生一对明显的氧化还原峰,且氧化峰电流与其浓度在2.0×10-6~3.0×10-4mol/L范围内呈良好的线性关系,方法检出限为2.08×10-7mol/L。该修饰电极用于实际样品中DA的测定,回收率达98.4%。     

普鲁士蓝-多壁碳纳米管复合材料修饰电极测定过氧化氢

利用电化学方法在多壁碳纳米管(MWCNT)修饰的玻碳电极表面聚合一层普鲁士蓝(PB)(PB/MWCNT/GCE),制备了一种新型的过氧化氢(H2O2)传感器。研究了该传感器对H2O2的电催化作用。讨论了支持电解质种类、酸度、修饰层厚度、电位和扫速等对H2O2响应的影响。研究表明,该传感器在以1.0mol/L KCl为支持电解质的磷酸盐溶液(pH=2.0)中,对H2O2具有明显的催化效应,测定的线性范围变宽,在2.9×10-6~8.8×10-2mol/L范围内还原峰电流与H2O2的浓度呈良好的线性关系,相关系数为0.9949;检出限为1.4×10-6mol/L。该电极用于医用消毒水中H2O2的测定,结果令人满意。     

镍纳米粒子-离子液体修饰碳糊电极的制备及其对多巴胺的测定

制备了镍纳米粒子-离子液体修饰电极,在0.1 mol/L磷酸缓冲溶液(pH 6.0)中研究了多巴胺(DA)在修饰电极上的电化学行为.与裸电极相比,DA在该修饰电极上的氧化还原电位明显降低,氧化还原反应的峰电流明显增大,DA的峰电流与其浓度在2.0×10~(-8) ～1.0×10~(-4) mol/L范围内呈良好的线性关系,检出限为6.5×10~(-9) mol/L.该修饰电极对抗坏血酸具有明显的抗干扰能力.     

Direct electrochemistry behavior of cytochrome c/L-cysteine modified electrode and its electrocatalytic oxidation to nitric oxide

Cytochrome c (Cyt c) was successfully immobilized on L-cysteine modified gold electrode by multicyclic voltammetry method. The electrochemical behavior of Cyt c on the L-cysteine modified electrode was explored. In 0.10 M, pH 7.0 phosphate buffer solution (PBS), Cyt c showed a quasi-reversible electrochemical redox behavior with E(pc)=0.180 V, E(pa)=0.208 V (versus Ag/AgCl). The Cyt c/L-cysteine modified electrode gave an excellent electrocatalytic activity towards the oxidation of nitric oxide, and the catalysis currents were proportional to the nitric oxide concentration in the range of 7.0 x 10(-7) to 1.0 x 10(-5) M, the linear regression equation is I (microA)=-0.124-0.003 C(NO) (microM), with a correlation coefficient 0.996, The detection limit was 3.0 x 10(-7) M (times the ratio of signal to noise, S/N=3).     

细胞色素c在硒代胱氨酸修饰电极上的直接电化学

采用电化学和接触角实验方法研究了硒代胱氨酸自组装膜修饰金电极(SeCys SAMs/Au)和十六烷基三甲基溴化铵(CTAB)-硒代胱氨酸自组装复合膜修饰金电极(CTAB-SeCys SAMs/Au)的特性. 探讨了细胞色素c(Cyt c)在SeCys SAMs/Au电极和CTAB-SeCys SAMs/Au电极上的电化学行为. 实验证明SeCys可促进Cyt c在电极上的氧化还原反应, 加入CTAB后其与SeCys之间的协同作用可在Cyt c与电极之间形成一个开放的通道, 促进作用更加明显, 且在一定浓度范围内, 随CTAB浓度(1×10^-5-1×10^-4 mol·L^-1)的增大, Cyt c在CTAB-SeCys SAMs/Au电极上的氧化还原电流增大, 在接近临界胶束浓度处出现极大值. 在CTAB-SeCys SAMs/Au电极上Cyt c产生一对氧化还原峰, 其峰电位分别为0.305和0.235 V, 其电化学过程受扩散控制. 光谱实验证实SeCys对Cyt c电化学过程的促进作用是由于SeCys与Cyt c中赖氨酸残基的结合.     

Amperometric nitrite biosensor based on a gold electrode modified with cytochrome c on Nafion and Cu-Mg-Al layered double hydroxides

An amperometric biosensor for nitrite was prepared by immobilizing cytochrome c (Cyt c) on a gold electrode that was modified with Nafion and a Cu-Mg-Al layered double hydroxide (Cu-LDH). The Cu-LDH was characterized by Fourier transform infrared spectroscopy and powder X-ray diffraction. The UV-visible spectrum suggests that Cyt c retains its native conformation in the modified film. The direct electrochemical investigation indicated that the composite film represents a good platform for the immobilization of Cyt c as well as an excellent promoter for the electron transfer between Cyt c and the gold electrode. Moreover, the biosensor showed a remarkable bioelectrocatalytic activity for the oxidation of nitrite with a linear range from 0.75 to 123 μM. The detection limit is 2?×?10^?7 M (S/N?=?3). The biosensor was successfully applied to the determination of nitrite in food samples.     

基于ITO电极的细胞色素c吸附层的直接电化学

采用未经修饰的铟锡氧化物(ITO)工作电极直接探测到了细胞色素c(Cytc)吸附层的氧化还原峰,并得出了Cytc的表面浓度,随着溶液浓度从2μmo·lL-1增大到10μmo·lL-1,Cytc的表面浓度相应地从0.35×10-12mo·lcm-2增大到1.53×10-12mo·lcm-2.实验获得的表面浓度倒数与溶液浓度倒数的准线性关系说明Cytc在ITO表面的吸附基本满足Langmuir等温吸附理论.对Cytc溶液的循环伏安测试结果表明参与电极反应的Cytc包括游离分子和吸附分子,前者的贡献大于后者,电极反应主要受扩散控制并呈准可逆过程.根据Nicholson方法估算得到反应物的标准异相速率常数的平均值为1.65×10-3cm·s-1.实验结果显示在室温下放置1h后Cytc吸附层电化学活性部分丧失,在80℃下放置1h后吸附层完全失活.失活的Cytc吸附层对铁氰化钾溶液在Au电极上的电极反应具有明显的阻碍作用.     

Direct electrochemistry behavior of Cytochrome c on silicon dioxide nanoparticles-modified electrode

A newfangled direct electrochemistry behavior of Cytochrome c (Cyt c) was found on glassy carbon (GC) electrode modified with the silicon dioxide (SiO2) nanoparticles by physical adsorption. A pair of stable and well-defined redox peaks of Cyt c′ quasi-reversible electrochemical reaction were obtained with a heterogeneous electron transfer rate constant of 1.66×10-3 cm/s and a formal potential of 0.069 V (vs. Ag/AgCl) (0.263 V versus NHE) in 0.1 mol/L pH 6.8 PBS. Both the size and the amount of SiO2 nanoparticles could influence the electron transfer between Cyt c and the electrode. Electrostatic interaction which is between the negative nanoparticle surface and positively charged amino acid residues on the Cyt c surface is of importance for the stability and reproducibility toward the direct electron transfer of Cyt c. It is suggested that the modification of SiO2 nanoparticles proposes a novel approach to realize the direct electrochemistry of proteins.     

纳米ZnO修饰电极的制备及其对血红蛋白, 细胞色素c的直接电化学研究

A novel electrochemical method as a sensitive and convenient technique for the determination of heme proteins based on their interaction with ZnO nanorods was developed. A ZnO nanorod modified glassy carbon electrode (ZnO/GCE) was prepared and the electrochemical behaviors of heme proteins, such as hemoglobin (HB) and cytochrome c (Cyt-c), on this modified electrode have been studied. The results showed that both HB and Cyt-c could be oxidized on the modified electrode and the oxidation currents were linear to the concentrations of the analytes in aqueous solutions. In addition, the results of flow injection analysis (FIA) further suggested the high stability and reproducibility of the ZnO nanorod modified electrode. So this method can be applied to the determination of HB and Cyt-c in biological systems.     

Direct electrochemical behavior of cytochrome c, and its determination on phytic acid modified electrode

Phytic acid (PA) with its unique structure was attached to a glassy carbon electrode (GCE) to form PA/GCE modified electrode which was characterized by electrochemical impedance. The electrochemical behavior of cytochrome c (Cyt c) on the PA/GCE modified electrode was explored by cyclic voltammetry and differential pulse voltammetry. The Cyt c displayed a quasi-reversible redox process on PA modified electrode pH 7.0 phosphate buffer solution with a formal potential (E ^0′) of 57 mV (versus Ag/AgCl). The peak currents were linearly related to the square root of the scan rate in the range of 20–120 mV·s^?1. The electron transfer rate constant was determined to be 12.5 s^?1. The PA/GCE modified electrode was applied to the determination of Cyt c, in the range of 5?×?10^?6 to 3?×?10^?4 M, the currents increase linearly to the Cyt c concentration with a correlation coefficient 0.9981. The detection limit was 1?×?10^?6 M (signal/noise?=?3).     

细胞色素c在纳米杂化膜修饰玻碳电极上的直接电化学

以多壁碳纳米管(MWNTs)修饰玻碳(GC)电极为基底,自组装金纳米粒子(AuNPs)及L-半胱氨酸(L-Cys)研制杂化膜修饰电极(L-Cys/AuNPs/MWNTs/GC).实验表明,该膜修饰电极在pH=7.0的KH2PO4-K2HPO4缓冲溶液中对细胞色素c(Cyt c)的直接电子转移反应具有良好的电催化作用,C...     

细胞色素c在自组装纳米膜电极上的有效固定及直接电化学

采用自组装方法将壳聚糖-纳米金(Chi-Nano Au)修饰到金(Au)电极上,并经进一步自组装细胞色素c(Cyt c),制得自组装膜电极Cyt c/Chi-Nano Au/Au.测定了自组装膜电极的循环伏安曲线(CV)及稳定性.结果表明,利用自组装膜电极Chi-Nano Au/Au可以有效地固定Cyt c,并实现直接电子转移反应.Cyt c在0.13～0.28V(vs Ag/AgCl)之间显示一对明显的可逆氧化还原峰;峰电流与扫描速度呈现良好的线性关系,线性方程为Ipc=0.063 64+0.003 51υ,线性相关系数为r=0.997 2,这表明该电极过程受吸附控制.此外,所制备的膜电极稳定性良好.     

Biomaterial engineered electrodes for bioelectronics

A series of single-cysteine-containing cytochrome c, Cyt c, heme proteins including the wild-type Cyt c (from Saccharomyces cerevisiae) and the mutants (V33C, Q21C, R18C, G1C, K9C and K4C) exhibit direct electrical contact with Au-electrodes upon covalent attachment to a maleimide monolayer associated with the electrode. With the G1C-Cyt c mutant, which includes the cysteine residue in the polypeptide chain at position 1, the potential-induced switchable control of the interfacial electron transfer was observed. This heme protein includes a positively charged protein periphery that surrounds the attachment site and faces the electrode surface. Biasing of the electrode at a negative potential (-0.3 V vs. SCE) attracts the reduced Fe(II)-Cyt c heme protein to the electrode surface. Upon the application of a double-potential-step chronoamperometric signal onto the electrode, where the electrode potential is switched to +0.3 V and back to -0.3 V, the kinetics of the transient cathodic current, corresponding to the re-reduction of the Fe(III)-Cyt c, is controlled by the time interval between the oxidative and reductive potential steps. While a short time interval results in a rapid interfacial electron-transfer, ket1 = 20 s-1, long time intervals lead to a slow interfacial electron transfer to the Fe(III)-Cyt c, ket2 = 1.5 s-1. The fast interfacial electron-transfer rate-constant is attributed to the reduction of the surface-attracted Fe(III)-Cyt c. The slow interfacial electron-transfer rate constant is attributed to the electrostatic repulsion of the positively charged Cyt c from the electrode surface, resulting in long-range electron transfer exhibiting a lower rate constant. At intermediate time intervals between the oxidative and reductive steps, two populations of Cyt c, consisting of surface-attracted and surface-repelled heme proteins, are observed. Crosslinking of a layered affinity complex between the Cyt c and cytochrome oxidase, COx, on an Au-electrode yields an electrically-contacted, integrated, electrode for the four-electron reduction of O2 to water. Kinetic analysis reveals that the rate-limiting step in the bioelectrocatalytic reduction of O2 by the integrated Cyt c/COx electrode is the primary electron transfer from the electrode support to the Cyt c units.